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Metriorhynchus
|Row 2 info = Mesoeucrocodylia |Row 3 title = Suborder |Row 3 info = Thalattosuchia |Row 4 title = Family |Row 4 info = Metriorhynchidae |Row 5 title = Genus |Row 5 info = Metriorhynchus von Meyer, 1830Meyer H Von. 1830. Achte Versammlung der Naturforscher und Aerzte zu Heidelberg im September 1829. Isis von Oken, 1830: 517-519. |Row 6 title = Species |Row 6 info = * M. geoffroyii von Meyer, 1832 (type) Meyer H von 1832. Paleologica zur Geschichte der Erde. Franfurt am Main, 560 pp. * M. hastifer (Eudes-Deslongchamps, 1867) * M. acutus Lennier, 1887Lennier G. 1887. Description des fossiles du Cap de la Hève. Bulletin de la Société Géologique de Normandie, Le Harve 12: 17-98. * M. palpebrosus (Phillips, 1871) * M. superciliosus (Blainville, 1853) * M. brachyrhynchus (Eudes-Deslongchamps, 1867) * M. durobrivensis (Lydekker, 1890) Andrews, 1913 * M. leedsi Andrews, 1913Andrews CW. 1913. A descriptive catalogue of the marine reptiles of the Oxford Clay, Part Two. London: British Museum (Natural History), 206 pp. * M. casamiquelai Gasparini & Chong, 1977 Gasparini Z, Chong G. 1977. Metriorhynchus casamiquelai n. sp. (Crocodilia, Thalattosuchia) a marine crocodile from the Jurassic (Callovian) of Chile, South America. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 153 (3): 341-360. * M. westermanni Gasparini, 1980 Gasparini ZB. 1980. Un nuevo cocodrilo marino (Crocodylia, Metriorhynchidae) del Caloviano del norte de Chile. Ameghiniana 17: 97–103. * M. potens Rusconi, 1948 |Row 7 title = Synonyms |Row 7 info = * Suchodus Lydekker, 1890 * Purranisaurus Rusconi, 1948 Rusconi C. 1948. Nuevo plesiosaurio, pez y langostas del mar jurasico de Mendoza. Mendoza, Mus. Hist. Nat., Rev. 2''': 3–12. }} ''Metriorhynchus'' is an extinct genus of marine crocodyliform that lived in the oceans during the Middle to Late Jurassic. Metriorhynchus was named by the German palaeontologist Christian von Meyer in 1830. Metriorhynchus was a carnivore that spent much, if not all, its life out at sea. No Metriorhynchus eggs or nests have been discovered, so little is known of the reptile's lifecycle, unlike other large marine reptiles of the Mesozoic, such as plesiosaurs or ichthyosaurs which are known to give birth to live young out at sea. Where Metriorhynchus mated, whether on land or at sea, is currently unknown. The name Metriorhynchus means "Moderate snout", and is derived from the Greek Metrio- ("moderate") and -''rhynchos'' ("snout"). Discovery and species Fossil specimens referrable to Metriorhynchus are known from Middle-Late Jurassic deposits of England, France, Germany,Steel R. 1973. Crocodylia. Handbuch der Paläoherpetologie, Teil 16. Stuttgart: Gustav Fischer Verlag,116 pp. Argentina,Gasparini Z. 1975. Revison de ?Purranisaurus potens RUSCONI, 1948 (Crocodilia, Thalattosuchia). Los Thalattosuchia como un nuevo Infraorden de los Crocodilia. Actas del Congreso Geologico Argentino '''5: 423–431. and Chile. Valid species Species in this genus are traditionally classed into two skull groups: longirostrine (long, narrow jaws) and brevirostrine (short, broad jaws). However there has been some contention as to how many of these species are valid, especially those from the Callovian. *Eudes-Deslongchamps (1867-69) found there to be four Callovian species: M. superciliosus, M. moreli, M. blainvillei, and M. brachyrhynchus.Eudes-Deslongchamps E. 1867-1869. Notes Paléontologiques. Caen and Paris: 320-392. *Andrews (1913) considered there to be seven valid species: M. superciliosus, M. moreli, M. brachyrhynchus, M. durobrivensis, M. cultridens, M. leedsi and M. laeve. *Adams-Tresman (1987) using linear morphometrics however could only distinguish between the two skull groups, so she found there to be two species: M. superciliosus and M. brachyrhynchus.Adams-Tresman SM. 1987. The Callovian (Middle Jurassic) marine crocodile Metriorhynchus from Central England. Palaeontology 30 (1): 179-194. *Vignaud (1997) however, considered there to be three Callovian species: M. superciliosus, M. brachyrhynchus and M. leedsi.Vignaud P. 1997. La morphologie dentaire des Thalattosuchia (Crocodylia, Mesosuchia). Palaeovertebrata 26: 35-59. Longirostrine *''M. superciliosus'': Western Europe (England and France) of the Middle-Late Jurassic (Callovian and Oxfordian); M. moreli, M. blainvillei, and M. jaekeli are junior synonyms. *''M. leedsi'': Western Europe (England) of the Middle Jurassic (Callovian); M. laeve is a junior synonym. *''M. palpebrosus'': Western Europe (England) of the Late Jurassic (Kimmeridgian); M. temporalis is a junior synonym. *''M. hastifer'': Western Europe (France) of the Late Jurassic (Kimmeridgian) *''M. acutus'': Western Europe (France) of the Late Jurassic (Kimmeridgian) *''M. geoffroyii'': (type species) Western Europe (France) of the Late Jurassic (Kimmeridgian) Brevirostrine *''M. brachyrhynchus'': Western Europe (England and France) of the Middle-Late Jurassic (Callovian and Oxfordian); M. cultridens is a junior synonym. *''M. durobrivensis'': Western Europe (England and France) of the Middle Jurassic (Callovian). Was originally the type species of the genus Suchodus, but it was regarded as a junior synonym of Metriorhynchus by Andrews, 1913. *''M. casamiquelai'': Middle Jurassic of Chile (Callovian); *''M. westermanni'': Middle Jurassic of Chile (Callovian). Although previously considered a junior synonym of M. casamiquelai,Gasparini Z, Vignaud P, Chong G. 2000. The Jurassic Thalattosuchia (Crocodyliformes) of Chile: a paleobiogeographic approach. Bulletin Société Géologique de France 171 (6): 657-664 it has been revalidated; Gasparini ZB, Paulina-Carabajal A, Chong G. 2008. Un nuevo espécimen de cocodrilo marino del Jurásico Medio del norte de Chile: revalidación de Metriorhynchus westermanni (Crocodyliformes: Metriorhynchidae). Revista Geológica de Chile 35 (2): 335-346. *''M. potens'': End Jurassic of Argentina (Tithonian). Was originally the type species of the genus Purranisaurus, but it was regarded as a possible junior synonym of Metriorhynchus by Gasparini. Unnamed species Fragmentary remains of Metriorhynchus are known from South America during the Bajocian and Bathonian (both Middle Jurassic).Gasparini Z, Cichowolski M, Lazio DG. 2005. First record of Metriorhynchus (Reptilia: Crocodyliformes) in the Bathonian (Middle Jurassic) of the Eastern Pacific. Journal of Paleontology 79 (4): 801–805. Taxonomy and phylogeny The genera Purranisaurus and Suchodus are junior synonyms of Metriorhynchus, Recent phylogenetic analyses however, do not support the monophyly of Metriorhynchus.Young MT. 2007. The evolution and interrelationships of Metriorhynchidae (Crocodyliformes, Thalattosuchia). Journal of Vertebrate Paleontology 27 (3): 170A.Gasparini Z, Pol D, Spalletti LA. 2006. An unusual marine crocodyliform from the Jurassic-Cretaceous boundary of Patagonia. Science 311: 70-73.Wilkinson LE, Young MT, Benton MJ. 2008. A new metriorhynchid crocodilian (Mesoeucrocodylia: Thalattosuchia) from the Kimmeridgian (Upper Jurassic) of Wiltshire, UK. Palaeontology 51 (6): 1307-1333. Some of the longirostrine forms, however, do appear to form a natural group.Mueller-Töwe IJ. 2005. Phylogenetic relationships of the Thalattosuchia. Zitteliana A45: 211–213. Palaeobiology Description , Paris.]] Averaging 3 meters (9.8 ft) in length, Metriorhynchus was of a similar size to modern crocodiles. However, it had a streamlined body and a finned tail, making it a more efficient swimmer than modern crocodilian species.Massare JA. 1988. Swimming capabilities of Mesozoic marine reptiles; implications for method of predation. Paleobiology 14 (2):187-205. Salt glands Recent examination of the fossil specimens of Metriorhynchus superciliosus, have shown that adults of this species had well-developed salt glands.Gandola R, Buffetaut E, Monaghan N, Dyke G. 2006. Salt glands in the fossil crocodile Metriorhynchus. Journal of Vertebrate Paleontology 26 (4): 1009-1010. This means that like Geosaurus it would have been able to "drink" salt-water (necessary for a pelagic animal) and eat prey that have the same ionic concentration as the surrounding sea water (i.e. cephalopods) without dehydrating.Fernández M, Gasparini Z. 2008. Salt glands in the Jurassic metriorhynchid Geosaurus: implications for the evolution of osmoregulation in Mesozoic crocodyliforms. Naturwissenschaften 95: 79-84. Diet Metriorhynchus was a versatile and opportunistic predator, predated upon both the armoured belemnites, fast moving fish and the giant filter feeding fish Leedsichthys. Occasionally it was also capable of capturing flying animals such as the pterosaurs and scavenging on plesiosaur carcasses on the seafloor. Forrest R. 2003. Evidence for scavenging by the marine crocodile Metriorhynchus on the carcass of a plesiosaur. Proceedings of the Geologists’ Association 114: 363-366. Palaeoecology Predators Even though Metriorhynchus was an effective predator, it was vulnerable to predation from apex predators such as Liopleurodon which could grow in excess of 10 metres in length. Since Metriorhynchus had lost its osteoderms, "armour scutes", to become more efficient swimmers it would have had little defence against larger marine predators. See also *List of marine reptiles References Suggested reading *Buffetaut E. 1982. Radiation évolutive, paléoécologie et biogéographie des Crocodiliens mésosuchienes. Mémoires Societé Geologique de France 142: 1–88 External links * Metriorhynchus fact files Category:Jurassic crocodylomorpha Category:Marine crocodiles Category:Prehistoric reptiles of Europe